In the beginning...
In the beginning God created the heavens and the earth. (Genesis 1:1 ESV)
How should this be understood? Without any other information it seems to describe what happened. However, a created earth is at odds with the next verse, and the events of days two and three, and verse 2:4 which states the earth was made in a day, not in the beginning.1
In his commentary of Genesis, H.C. Leupold notes it is "a characteristic Hebrew way of summarizing the whole story before the details are given."2
Here is an example:
Thus Isaac sent Jacob away. And he went to Paddan-aram, to Laban, the son of Bethuel the Aramean, the brother of Rebekah, Jacob's and Esau's mother. (Genesis 28:5 ESV)
After stating Jacob went to Paddan-aram the narrative continues by describing events which occurred in Bethel not Paddan-aram.
This method of recording history is consistent with what God declares about Himself:
9 remember the former things of old;
for I am God, and there is no other;
I am God, and there is none like me,
10 declaring the end from the beginning
and from ancient times things not yet done,
saying, ‘My counsel shall stand,
and I will accomplish all my purpose,’ (Isaiah 46)
Upon reading all of Genesis, the first verse should be understood as a summary statement. In contrast to Babylonian and Egyptian stories, Genesis begins by making the point God did all of the work without opposition or help from other gods.
Genesis 1:1 does not contain any details of creation nor does it have an explicit answer to the question of "why" God created. However, since the Bible is God's revelation to man, a reasonable interpretation of the summary is, In the beginning [of revealing Himself] God created the heavens and the earth. Only after making this summary are selected details provided.
Evening and Morning...
The issue of time is central to both theological and scientific questions about the Genesis narrative. There are three aspects to the issue: (1) The unit of measure, days. (2) Declaring the demarcation between days as evening and morning. (3) The period covered is seven-days (168 hours).
There can be no physical evening and morning until after the fourth day, but, with respect to measuring time, this is a non-issue. To illustrate, consider how years are used to report the age of creation as 13.8 billion, and the age of the sun as 4.6 billion and the earth as 4.5 billion. How is possible to measure almost 9 billion years before the sun and earth exist? The answer is by making observations in the created world and establishing a standard unit of measure. Then, based on the assumption time is continuous and unchanging, the age of things may be estimated. Setting aside questions on the accuracy of scientific estimates, the important consideration is recognizing this approach measures time retrospectively.
Unlike science Genesis reports time proleptically. Without need of earth and sun, God is able to declare there was evening and morning...the...day. Proleptic and retrospective methods are "two sides of the same coin." It is not logical to question the necessity of an actual evening and morning in order to measure a day while claiming the "correct" time should be given in years, 9 billion which are measured without the sun or earth.
Any method of reporting time from the beginning comes with certain assumptions. The chosen unit of measure does not vary, is continuous, and is contiguous. With respect to Genesis, these three are present. Since an actual day is from evening to evening, morning occurs during a day. The statement evening and morning...the day demonstrates a day is not counted until morning of the following day. This method of counting demands each day be contiguous with the next. Gaps are impossible. Coincidentally, even though evening and morning implies darkness, the narrative is given so as to report every work as occurring while it is light, after it is morning.
Lacking any evidence to the contrary, counting days consecutively implies each day is measuring the same period of time, 24-hours. This is confirmed elsewhere:
8 “Remember the Sabbath day, to keep it holy. 9 Six days you shall labor, and do all your work, 10 but the seventh day is a Sabbath to the LORD your God. On it you shall not do any work, you, or your son, or your daughter, your male servant, or your female servant, or your livestock, or the sojourner who is within your gates. 11 For in six days the LORD made heaven and earth, the sea, and all that is in them, and rested on the seventh day. Therefore the LORD blessed the Sabbath day and made it holy. (Exodus 20)
12 And the LORD said to Moses, 13 “You are to speak to the people of Israel and say, ‘Above all you shall keep my Sabbaths, for this is a sign between me and you throughout your generations, that you may know that I, the LORD, sanctify you. 14 You shall keep the Sabbath, because it is holy for you. Everyone who profanes it shall be put to death. Whoever does any work on it, that soul shall be cut off from among his people. 15 Six days shall work be done, but the seventh day is a Sabbath of solemn rest, holy to the LORD. Whoever does any work on the Sabbath day shall be put to death. 16 Therefore the people of Israel shall keep the Sabbath, observing the Sabbath throughout their generations, as a covenant forever. 17 It is a sign forever between me and the people of Israel that in six days the LORD made heaven and earth, and on the seventh day he rested and was refreshed.’” (Exodus 31)
While the amount of time is disputed, the fact is science makes and uses the same considerations as found in the Bible to calculate and offer an alternative duration.
There is a significant "scientific" aspect of God's proleptic use of evening and morning. Scientifically speaking, "what if" the earth and sun did exist from the beginning? When it is evening somewhere, it is morning on the other side of the earth. Speaking globally, it is always evening and morning simultaneously. Exact measurements of evening and morning such as are understood after the seventh day require a fixed location. Therefore, the primary significance of God's proleptic method of measuring specific days, is to declare there will be a unique location on the earth at which a day begins and ends. Based upon the New Testament, that location is where Jesus was crucified.
God's measuring of time not only looks ahead to the work of creating earth and the sun; it looks ahead to the work of salvation. Likewise, when the New Testament states eternal life is traced from the tree on which Jesus was crucified, this follows the pattern in Genesis which states physical death is traced from a tree. As the Bible says, declaring the end from the beginning.
Plants
Creating plants before the sun is a non-issue if the length of a day is 24-hours. First, no vegetation will die from 24-hours of darkness. That assumes there any darkness present. God separated the light from the darkness so there is no reason to insert darkness into the process of creation. Furthermore God's work is always described as taking place after it is morning and before evening. This picture means after be light... nothing was done in darkness. Since God is light in whom there is no darkness (1 John 1:5), there is no reason think evening also brings darkness.
Stars
The Bible states stars were created to give light to the earth. The Big Bang Theory claims the first "stars" which formed no longer exist. According to the theory, only two elements, hydrogen and helium are a direct result of the initial event. The other 116 elements were formed by stellar nucleosynthesis. After the stars exploded, the elements will be found throughout the universe.3
According to the theory, the heavy elements which are found on the earth had to have come from "stars" formed before the sun: stars which no loner exist. There is a certain irony in a theory which demands physical material found on the earth, be from the oldest stars whose light may still be observed from the earth. Even more ironic is a theory which states stellar nucleosyntheses, a process of fusion which consumes the original hydrogen and helium make up of star, somehow fails to function that way in the oldest stars, whose makeup remains only hydrogen and helium and whose light is still visible from the earth.
Over and over again science discovers anomalies which, according to the laws of nature, are impossible...yet God's miraculous works described in the Bible are called myths. The parting of the Red Sea is a myth, but the oldest star, Methuselah is real. The laws of gravity are real, yet the universe underwent a second expansion event, contrary to the laws of gravity. Science proclaims two unique expansion events which define the universe. What does the Bible say?
....And God separated the light from the darkness. (Genesis 1:4)
...and to separate the light from the darkness. (Genesis 1:18)
On the first day God separated light from dark energy and on the fourth day He separated light from dark matter. The Hebrew word translated as separate is בָּדַל, which is often rendered as to divide. What began as a whole was divided. In other words, the darkness occupied more space:

Science states the universe is 95% dark energy and dark matter, neither of which interact with light. Science fails to state the Bible says God separated light from darkness.
Birds
Science disputes the sequence of fish, birds, and land animals by saying the fossil evidence shows birds are more recent then land animals.
However, fossils are evidence of when an animal died. So the appropriate way to report the evidence is to say the fossil evidence shows the first animals to die were fish, then land animals, and finally birds. The Bible states death entered creation as a result of man. The question from a Biblical perspective is how would man's impact on the environment affect animal life? Man's immediate impact is on the physical world (think of climate change) not the animal kingdom. Any change to the environment would most likely first affect aquatic life.
If the Bible is correct about the reason for death, one would predict fish to die before either birds or land animals. Between birds and land animals, one would predict birds to be the last to be affected. They are best suited to avoid man and any harm brought to the environment. The fossil record is in agreement with the Biblical explanation for death in the created world.
Conclusion...How Old?
The OP does not raise the question of age: is the earth old or new? I would like to conclude by addressing this question in terms of dating fossils with 14C.
Carbon-14 (14C) occurs naturally; natural 14C is from a physical process established by God. The half-life of 14C is 5,730 years with an uncertainty of 40 years. If the age of the earth is about 6,000 years, then one would expect every fossil to have some amount of 14C. Is this the case?
Furthermore, if Genesis is a factual account of creation, one would expect the oldest fossils to have smaller amounts of 14C. Not because they are millions of years old, because Biblically speaking, most fossils are from animals who died less than one half-life of 14C. The older animals lived and died at a time the environment had smaller amounts of 14C.
Rather than search for life outside the earth, science should contemplate the significance of the carbon based life on earth. The Biblical number of man is six; carbon is the sixth element. Salvation is of the Jews and there were 12 tribes; the atomic number of carbon is 12. When Jacob adopted Joseph's two sons, the list of names for the 12 tribes increased to 14. When Christ returns the list of names will be restored to 12. In other words, 14 names is unstable, just as 14C is unstable. When the Bible was written there was no knowledge of carbon or 14C. How does one explain the accuracy of the Bible's proclamation of salvation and carbon based life and death?
Finally, I am not surprised to learn carbon-14 was discovered by two men working together, Martin Kamen and Samuel Ruben. Both men were Jews. Their discovery was made in 1940, approximately 5,700 years, one half-life of 14C after creation. How miraculous! Two Jewish scientists discovered carbon-14 at a point in Biblical history equal to the first half-life 14C.
Do not settle merely for intelligent design. Believe the blue print of creation given by God. Find salvation in ערב ויהי־בקר.
1. If a day is 24-hours, the "day" in Genesis 2:4 would be the 24-hour period which began during the second day and ended during the third day.
2. H.C. Leupold D.D., Exposition of Genesis, Baker Book House, 1960, Volume II, p. 770.
3. Proponents of intelligent design will argue the laws of thermodynamics prevent an explosion from bringing order. Rather then go down that road, I believe it would be better to point to the absurdity of the need for numerous explosions, possibly in the millions which the Big Bang Theory requires for the earth to even exist as a lifeless inorganic object.